This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 arising from an application entitled, RESOURCE ASSIGNMENT METHOD ACCORDING TO THE DATA TRANSMISSION TYPES IN WIRELESS LOCAL LOOP SYSTEM, earlier filed in the Korean Industrial Property Office on Sep. 8, 1998, and there duly assigned Serial No. 1998-36974.
The present invention relates to a wireless local loop (WLL) system, and more particularly a method for allocating and releasing communication resources at different data transmission rates in a base station controller of the WLL system.
The WLL system, using Wideband Code Division Multiple Access(CDMA) technology, allows a subscriber of a fixed telephone unit to be connected to a central office through radio links. The function of WLL system is basically the same as mobile communication system, except that it does not provide mobility for the fixed subscriber unit. In comparison to other system, the WLL system is considered to be more economical and faster in providing communication services, i.e., voice data and packet data via facsimile, internet service, etc.
FIG. 1 is a block diagram of WLL system according to prior art, which includes a plurality of telephones(10), a fixed subscriber unit (FSU)(20) coupled to the telephones, a plurality of radio carrier station(RCS)(30) coupled to the FSUs for providing radio links to both the FSU and the telephones, a radio distribution unit(RDU)(40) coupled to the RCSs which interfaces with a local exchange(LE)(50) through trunk links, and a public switched telephone network(PSTN)(60) for connecting the LE with other network.
Typically, the WLL system uses 64 kbps Pulse Code Modulation(PCM) data transmission for compacting the voice data, and 32 kbps Adaptive Differential PCM(ADPCM) data transmission, and 16 kbps Low Delay Code Excited linear Prediction(LD-CELP) data transmission for further improving the compression ratio of the voice data.
Since the rate of data transmission differs among various subscribers, the data received at the RDU through the trunk link tends to overlap with each other. That is, in the prior art, it is not possible to know which sub-time slot is being used for which transfer rate, causing error at the recovery stage.
One object of the present invention is to provide a method for allocating and releasing communication resources at different data transmission rates in the WLL system, by allocating time slots of trunk channels to accommodate different data transmission rate.
Other object of the present invention is to provide a method for allocating and releasing communication resources at different data transmission rates in the WLL system in order to increase the capacity of trunks to accommodate more subscribers and improve the recovery error, and the different data transmission rate includes 64 kbps PCM, 32 kbps ADPCM, and 16 kbps PCM.
Other objects and advantages of the present invention will become apparent with reference to the following detailed description and the attached drawings.